Typewell operations

let me briefly explain several common workflows that our customers use when operating with typewells. You may find them useful.

First of all, I want to clarify some terms regarding typewell:

Statement: Typewell is always vertical.

This statement is true for any geosteering software including StarSteer. It is the base principal for strat-based and model-based geosteering approaches used in any geosteering software including StarSteer.

When the typewell that you trying to use is not vertical, you need to verticalize it (project it to vertical plane in other words), some people call it TVD-correction of deviated well.

You can verticalize typewell using several different options:

1. The first approach - to load typewell as TVD-log_value. This is the simplest one but not the most efficient one. It is used when you don't have trajectory information for your typewell but have TVD information in your log files (las or txt).

It is the option that you are used to and you are currently using it in StarSteer.

In StarSteer you rename las file to txt and load TVD and log_value columns. The reason you can't load it directly from las file because las file format assumes that the logs are in MD-log_value format. Having TVD column there is rather an exception than common practice.

Anyway, to make your life easier, we will add the possibility to select the depth column - MD or TVD from las file, so you won't need to rename it to txt and spend time on that.

When you select TVD as a depth column, you are verticalizing your deviated well and losing your deviated component.

In the newly created verticalized typewell you will have MD=TVD because typewell is always vertical. Of course, we may say that as well as you loading typewell as TVD-log_value, there is no MD anymore for this well. But it is not true. By loading this well, you are verticalizing it and making MD=TVD for this well. This MD is different from MD in your original file because you are losing deviated component of the well while loading well like that.

Hope this concept is clear.

This approach #1 is not popular in geosteering industry because usually people have trajectory information for their typewells and don't have TVD information in log files. Some geosteering software in the industry pushes people to have TVD columns in their las files and use this approach as default one simply because this approach is the easiest to implement in their software.

2. The second approach - to use pseudo-typewell capabilities with the direct horizontal projection for typewell verticalization.

This approach is the most popular one and used almost by all our customers.

It can be used for deviated well with trajectory file available and doesn't require TVD information in log files.

The typical workflow is as follows:

- load trajectory of this well in MD-INCL-AZIM format from xls file as a new lateral, then load logs in MD-log_values format from las file for this well.

- use pseudo-typewells capabilities of StarSteer to verticalize the required logs of this well with direct horizontal projection. To do that:

Enter the Geosteering Process; Activate this well (double click on its name in the object tree to make it bold), create empty interpretation (it will create automatically if there no interpretation available)

Select GR for this well in the tree (or other logs that you want to get verticalized), go to Log Format, select Create Pseudo log

In opened window select Create from all the segments and enter the sampling rate, Ok

You will get your new TVD-corrected pseudo-typewell in the tree.

In v2016.1 (to be released by the end of Feb) we plan to add special button "Create vertical pseudo-log" for this approach to eliminate steps 1-3.

3. The third one - to use your existing geosteering interpretation in your lateral and create pseudo-typewell out of it.

This capability is very powerful and allows you to use your geosteered lateral as typewell. You not only using the data until the end of the curve, but the log information from the whole lateral.

The typical workflow is as follows:

- Make sure you have lateral well with logs and geosteering interpretation performed in StarSteer.

- use pseudo-typewells capabilities of StarSteer to verticalize the required logs.

To do that:

Enter the Geosteering Process; activate this well (double click on its name in the object tree to make it bold); activate your existing geosteering interpretation

Select GR for this well in the tree (or other logs that you want to get verticalized), go to Log Format, select Create Pseudo log

In opened window select Create from all the segments and enter the sampling rate, Ok (there is also an option to create it from visible segments only, in case you crossed certain interval couple times with you lateral)

You can check the video on pseudo-typewell creation on our youtube channel: